Sensor chip, process for producing the same, and sensor using the same

ABSTRACT

A sensor chip comprises a layer-shaped base body, which has a plurality of fine holes formed in one surface, and fine metal particles, each of which is loaded in one of the fine holes of the base body. At least a part of each of the fine metal particles is exposed to a side of the layer-shaped base body, which side is more outward than the one surface of the layer-shaped base body. The layer-shaped base body may be constituted of anodic oxidation alumina. The sensor chip constitutes a sensor utilizing localized plasmon resonance, with which a state of binding of a sensing medium with a specific substance is capable of being detected quickly and with a high sensitivity.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a sensor utilizing localized plasmonresonance. This invention also relates to a sensor chip for use in thesensor, and a process for producing the sensor chip. This inventionfurther relates to a fine structure body for use in the sensor of thetype described above, and a process for producing the fine structurebody.

[0003] 2. Description of the Related Art

[0004] As disclosed in, for example, Patent Literature 1, there haveheretofore been known sensors, in which a fine structure body comprisinga dielectric material, a semiconductor, or the like, and fine metalparticles secured in a layer-shaped form to a surface of the dielectricmaterial, the semiconductor, or the like, is employed as a sensor chip,and with which a refractive index of a sample, or the like, is measuredby the utilization of localized plasmon resonance. Basically, thesensors are provided with means for irradiating measuring light to thearea of the fine metal particles of the sensor chip, and photo detectingmeans for detecting intensity of the measuring light coming from thefine metal particles secured in the layer-shaped form (i.e., themeasuring light, which has passed through the fine metal particles, orthe measuring light, which has been reflected from the fine metalparticles).

[0005] With the sensors described above, when the measuring light isirradiated to the area of the fine metal particles secured in thelayer-shaped form, the localized plasmon resonance occurs at a certainspecific wavelength, and the scattering and the absorption of themeasuring light are caused by the localized plasmon resonance toincrease markedly. Therefore, in cases where the intensity of themeasuring light coming from the fine metal particles secured in thelayer-shaped form is detected, the markedly occurring attenuation of thedetected intensity of the measuring light is capable of being observed,and the occurrence of the localized plasmon resonance is thereby capableof being confirmed.

[0006] In such cases, the light wavelength, at which the localizedplasmon resonance occurs, and the extent of the scattering and theabsorption of the measuring light depend upon the refractive index ofthe medium, which is present around the fine metal particles.Specifically, in cases where the refractive index of the medium, whichis present around the fine metal particles, is large, a resonance peakwavelength shifts to the long wavelength side, and the scattering andthe absorption of the measuring light increase. Therefore, in caseswhere the measuring light is irradiated to the area of the fine metalparticles in a state in which a sample is located around the fine metalparticles secured in the layer-shaped form, and the intensity of themeasuring light coming from the area of the fine metal particles isdetected, the refractive index of the sample, physical properties of thesample corresponding to the refractive index, and the like, are capableof being measured.

[0007] In such cases, white light may be employed as the measuringlight, the light coming from the area of the fine metal particles may bedetected spectrophotometrically, and the shift of the resonance peakwavelength described above may thereby be detected. Alternatively,monochromatic light may be employed as the measuring light, and theshift of the resonance peak wavelength described above, and a change inlight intensity accompanying a change in scattering and absorption ofthe measuring light may thereby be detected.

[0008] Also, in order for the measuring light coming from the fine metalparticles secured in the layer-shaped form to be detected, aphotodetector may be located on the side with respect to the fine metalparticles, which side is opposite to the measuring light irradiationside, and the light having passed through the fine metal particles maythereby be detected. Alternatively, the photodetector may be located onthe side with respect to the fine metal particles, which side isidentical with the measuring light irradiation side, and the lighthaving been reflected from the fine metal particles may thereby bedetected. In the latter cases, a base body, to which the fine metalparticles are secured in the layer-shaped form, may be made from amaterial having light reflecting properties. In such cases, themeasuring light having passed through the fine metal particles isreflected from the base body. Therefore, the measuring light, which haspassed through the fine metal particles and has then been reflected fromthe base body, is capable of being detected together with the measuringlight, which has been reflected from the fine metal particles.

[0009] Further, in cases where a sensing medium, which is capable ofbinding with a specific substance, is fixed to peripheral areas of thefine metal particles of the sensor chip, the refractive index at theperipheral areas of the fine metal particles alters in accordance withthe occurrence of the binding of the sensing medium with the specificsubstance. Therefore, the measuring light may be irradiated to the areaof the fine metal particles in the state in which the sensing mediumdescribed above has been fixed to the peripheral areas of the fine metalparticles, and the intensity of the measuring light coming from the areaof the fine metal particles may be detected. In this manner, theoccurrence of the binding of the sensing medium with the specificsubstance is capable of being detected. The combination of the specificsubstance and the sensing medium may be, for example, the combination ofan antigen and an antibody.

[0010] As the sensor chip for use in the sensor utilizing the localizedplasmon resonance, for example, a sensor chip comprising a base body anda colloidal metal single-layer film, which is formed at a surface areaof the base body, has heretofore been known. The sensor chip comprisingthe base body and the colloidal metal single-layer film, which is formedat the surface area of the base body, is described in, for example,Patent Literature 1. Also, a fine structure body comprising layer-shapedanodic oxidation alumina, which has a plurality of fine holes formed inone surface, and fine metal particles, which are loaded in the fineholes of the anodic oxidation alumina, is applicable to the sensordescribed above. The aforesaid fine structure body is described in, forexample, Non-Patent Literatures 1 and 2. Anodic oxidation aluminaitself, which has a plurality of fine holes, is also described in, forexample, Patent Literature 2 and Non-Patent Literature 3.

[0011] As described in, for example, Non-Patent Literature 3, it hasalso been known that a plurality of fine holes having diameters rangingfrom approximately several nanometers to approximately 300 nm are formedin a regular pattern in an anodic oxidation alumina film which isobtained from anodic oxidation processing performed with Al in asolution.

[0012] A marked feature of the anodic oxidation alumina acting as aporous material is that the anodic oxidation alumina has a honeycombstructure, in which the fine holes are formed in parallel atapproximately equal intervals and extend in a direction approximatelynormal to the surface of the base plate. The anodic oxidation aluminaalso has the unique features in that the diameters of the fine holes,the intervals of the fine holes, and the depths of the fine holes arecapable of being adjusted comparatively freely.

[0013] As described in, for example, Non-Patent Literature 4, it hasalso been known that an anodic oxidation alumina film may be formed on abase plate constituted of GaAs or InP, and fine holes may be formed inthe GaAs base plate or the InP base plate with the anodic oxidationalumina film acting as a mask.

[0014] [Patent Literature 1]

[0015] U.S. Patent Laid-Open No. 20020089617

[0016] [Patent Literature 2]

[0017] Japanese Unexamined Patent Publication No. 11(1999)-200090

[0018] [Non-Patent Literature 1]

[0019] Journal of Applied Physics, Vol. 49, No. 5, p. 2929, 1978

[0020] [Non-Patent Literature 2]

[0021] Journal of Applied Physics, Vol. 51, No. 1, p. 754, 1980

[0022] [Non-Patent Literature 3]

[0023] “High-Regularity Metal Nano-Hole Array Based on Anodized Alumina”by Hideki Masuda, Solid Physics, Vol. 31, No. 5, p. 493, 1996

[0024] [Non-Patent Literature 4]

[0025] Masashi Nakano, et al., Jpn. J. Appl. Phys., Vol. 38, pp.1052-1055, 1999

[0026] A sensor chip comprising the layer-shaped base body, such as theanodic oxidation alumina, which has the plurality of the fine holesformed in one surface as described above, and the fine metal particles,which are loaded in the fine holes of the base body, is also capable ofbeing used for the operation, in which the sensing medium, which iscapable of binding with the specific substance, is fixed to peripheralareas of the fine metal particles, and the occurrence of the binding ofthe sensing medium with the specific substance is thereby detected.

[0027] However, in cases where the state of the binding of the sensingmedium with the specific substance is to be detected by use of theconventional sensor chip constituted in the manner described above, theproblems are encountered in that the change in sensor output signalarising due to the occurrence of the binding of the sensing medium withthe specific substance (i.e., the shift of the resonance peak wavelengthdescribed above, or the change in light intensity accompanying a changein scattering and absorption of the measuring light) is weak, and a longperiod of time is required before the change in sensor output signalarising due to the occurrence of the binding of the sensing medium withthe specific substance is found.

SUMMARY OF THE INVENTION

[0028] In view of the above circumstances, the first object of thepresent invention is to provide a sensor utilizing localized plasmonresonance, with which a state of binding of a sensing medium with aspecific substance is capable of being detected quickly and with a highsensitivity, and a sensor chip for use in the sensor.

[0029] In the cases of the anodic oxidation alumina film describedabove, due to features of crystal growth, a region in which thecomposition is nonuniform occurs between the holes. Therefore, theproblems occur in that, in cases where the anodic oxidation alumina filmis used in a sensor, or the like, the nonuniformity of the compositioncauses optical noise to occur and obstructs enhancement of asignal-to-noise ratio.

[0030] In view of the above circumstances, the second object of thepresent invention is to provide a sensor chip for use in a sensorwherein a state of localized plasmon resonance at a surface of each offine metal particles is detected by the utilization of light and whereincharacteristics of a sample in the vicinity of each of the fine metalparticles are thereby analyzed, which sensor chip allows measurementwith little noise and with a high sensitivity, a process for producingthe sensor chip, and a sensor using the sensor chip.

[0031] In the cases of the sensor using the conventional fine structurebody described above, the attenuation of the measuring light due to thelocalized plasmon resonance occurs over a comparatively wide wavelengthrange around the resonance peak wavelength. Specifically, with thesensor using the conventional fine structure body, the measuring lightabsorption and scattering spectral characteristics do not altersufficiently sharply. Therefore, with the conventional sensor, theproblems occur in that a slight change in refractive index of a sampleor physical properties of the sample and slight binding of a specificsubstance with a fixed substance cannot always be detected.

[0032] In view of the above circumstances, the third object of thepresent invention is to provide a sensor utilizing localized plasmonresonance, with which a slight change in refractive index of a sample ora slight change in physical properties of the sample is capable of beingdetected, a fine structure body for use in the sensor, and a process forproducing the fine structure body.

[0033] A first sensor chip in accordance with the present invention aimsat accomplishing the aforesaid first object of the present invention.Specifically, the present invention provides a first sensor chip,comprising:

[0034] i) a layer-shaped base body, which has a plurality of fine holesformed in one surface, and

[0035] ii) fine metal particles, each of which is loaded in one of thefine holes of the base body,

[0036] wherein at least a part of each of the fine metal particles isexposed to a side of the layer-shaped base body, which side is moreoutward than the one surface of the layer-shaped base body.

[0037] The first sensor chip in accordance with the present inventionshould preferably be modified such that the layer-shaped base body isconstituted of anodic oxidation alumina. Alternatively, the first sensorchip in accordance with the present invention may be modified such thatthe fine holes of the layer-shaped base body are formed with etchingprocessing, in which anodic oxidation alumina having a plurality of fineholes is utilized as a mask.

[0038] Also, the first sensor chip in accordance with the presentinvention should preferably be modified such that at least a one-halfpart of each of the fine metal particles is exposed to the side of thelayer-shaped base body, which side is more outward than the one surfaceof the layer-shaped base body. Further, the first sensor chip inaccordance with the present invention should preferably be modified suchthat a diameter of each of the fine metal particles is at most 200 nm.

[0039] The present invention also provides a first sensor using theaforesaid first sensor chip in accordance with the present invention,the sensor comprising:

[0040] i) means for irradiating measuring light to an area of the finemetal particles of the sensor chip, and

[0041] ii) photo detecting means for detecting intensity of themeasuring light, which has passed through the area of the fine metalparticles, or has been reflected from the area of the fine metalparticles.

[0042] The first sensor in accordance with the present invention shouldpreferably be modified such that the means for irradiating the measuringlight is means for producing white light as the measuring light, and

[0043] the photo detecting means spectrophotometrically detects theintensity of the measuring light, which has passed through the area ofthe fine metal particles, or has been reflected from-the area of thefine metal particles.

[0044] A second sensor chip in accordance with the present inventionaims at accomplishing the aforesaid second object of the presentinvention. Specifically, the present invention further provides a secondsensor chip for use in a sensor wherein a state of localized plasmonresonance at a surface of each of fine metal particles is detected bythe utilization of light and wherein characteristics of a sample in thevicinity of each of the fine metal particles are thereby analyzed, thesensor chip comprising:

[0045] i) a support member having a plurality of independent fine holes,which extend in a direction approximately normal to a surface of thesupport member, and

[0046] ii) independent fine metal particles, each of which is supportedwithin one of the fine holes of the support member,

[0047] wherein the support member is constituted of a transparentdielectric material having uniform density.

[0048] The second sensor chip in accordance with the present inventionshould preferably be modified such that the support member isconstituted of a polystyrene.

[0049] The present invention still further provides a process forproducing the aforesaid second sensor chip in accordance with thepresent invention. Specifically, the present invention still furtherprovides a process for producing a sensor chip, comprising the steps of:

[0050] i) forming an anodic oxidation alumina film on a surface of abase plate, which is constituted of a transparent dielectric material,the anodic oxidation alumina film having a plurality of first fineholes, which extend in a direction approximately normal to the surfaceof the base plate,

[0051] ii) subjecting the base plate to etching processing, in which theanodic oxidation alumina film having been formed on the surface of thebase plate is utilized as a mask, a plurality of second fine holes, eachof which corresponds to one of the first fine holes, being therebyformed in the surface of the base plate, and

[0052] iii) performing processing wherein, after the anodic oxidationalumina film has been removed from the surface of the base plate, ametal depositing operation is performed on the base plate having thesurface, in which the second fine holes have been formed, the metaldepositing operation being performed from the side of the surface of thebase plate, and a metal deposit layer having been formed on the surfaceof the base plate is then removed, whereby each of independent finemetal particles is supported within one of the second fine holes of thebase plate.

[0053] The present invention also provides a second sensor, comprising:

[0054] i) the aforesaid second sensor chip in accordance with thepresent invention,

[0055] ii) a light source for producing light, such that the lightimpinges upon an area of the fine metal particles of the sensor chip,and

[0056] iii) photo detecting means for detecting intensity of the light,which has passed through the area of the fine metal particles of thesensor chip, or has been reflected from the area of the fine metalparticles of the sensor chip,

[0057] wherein characteristics of a sample in the vicinity of each ofthe fine metal particles, each of which is supported within one of thefine holes of the support member, are analyzed in accordance withresults of measurement obtained from the photo detecting means.

[0058] The second sensor in accordance with the present invention shouldpreferably be modified such that the photo detecting means is aspectrophotometer.

[0059] The term “uniform density” as used herein means the density suchthat optical noise does not occur when the sensor chip is used in thesensor, and such that little nonuniform composition region, littledefect due to nonuniform composition, or the like, is present.

[0060] The term “transparent dielectric material” as used herein meansthe dielectric material, which substantially transmits the measuringlight for the detection of the localized plasmon resonance, i.e. thelight produced by the light source.

[0061] The term “vicinity of each of fine metal particles” as usedherein means the range from the surface of each of the fine metalparticles to a region located at a distance approximately equal to thediameter of each of the fine metal particles, i.e. the range in whichthe localized plasmon resonance occurs.

[0062] A fine structure body in accordance with the present inventionaims at accomplishing the aforesaid third object of the presentinvention. Specifically, the present invention further provides a finestructure body, comprising:

[0063] i) a layer-shaped base body, which has a plurality of fine holesformed in one surface,

[0064] ii) fine metal particles, each of which is loaded in one of thefine holes of the base body, and

[0065] iii) a thin metal film formed on areas of the one surface of thelayer-shaped base body, which areas are located around each of the fineholes of the layer-shaped base body, such that the thin metal film islocated at a spacing, which is approximately equal to at most a diameterof each of the fine metal particles, from each of the fine metalparticles.

[0066] The fine structure body in accordance with the present inventionshould preferably be modified such that the layer-shaped base body isconstituted of anodic oxidation alumina. Alternatively, the finestructure body in accordance with the present invention may be modifiedsuch that the fine holes of the layer-shaped base body are formed withetching processing, in which anodic oxidation alumina having a pluralityof fine holes is utilized as a mask.

[0067] Also, the fine structure body in accordance with the presentinvention should preferably be modified such that the layer-shaped basebody is transparent with respect to light irradiated to the layer-shapedbase body.

[0068] Further, the fine structure body in accordance with the presentinvention should preferably be modified such that the layer-shaped basebody is divided into a plurality of layer-shaped base sub-bodies, whichare located at a spacing from one another and are supported togetherwith one another.

[0069] The present invention still further provides a process forproducing the aforesaid fine structure body in accordance with thepresent invention, comprising the steps of:

[0070] i) obtaining the layer-shaped base body, which has the pluralityof the fine holes formed in the one surface, and

[0071] ii) performing vacuum evaporation processing from the side of theone surface of the layer-shaped base body, whereby each of the finemetal particles is loaded in one of the fine holes of the base body, andthe thin metal film is formed on the areas of the one surface of thelayer-shaped base body, which areas are located around each of the fineholes of the layer-shaped base body.

[0072] The present invention also provides a process for producing theaforesaid fine structure body in accordance with the present invention,comprising the steps of:

[0073] i) obtaining the layer-shaped base body, which has the pluralityof the fine holes formed in the one surface,

[0074] ii) performing plating processing on the layer-shaped base body,each of the fine metal particles being thereby loaded in one of the fineholes of the base body, and

[0075] iii) performing vacuum evaporation processing from the side ofthe one surface of the layer-shaped base body, whereby the thin metalfilm is formed on the areas of the one surface of the layer-shaped basebody, which areas are located around each of the fine holes of thelayer-shaped base body.

[0076] The present invention further provides a third sensor using theaforesaid fine structure body in accordance with the present invention,the sensor comprising:

[0077] i) means for irradiating measuring light to an area of the finemetal particles and the thin metal film of the fine structure body, and

[0078] ii) photo detecting means for detecting intensity of themeasuring light, which has passed through the area of the fine metalparticles and the thin metal film, or has been reflected from the areaof the fine metal particles and the thin metal film.

[0079] The third sensor in accordance with the present invention shouldpreferably be modified such that the photo detecting meansspectrophotometrically detects the intensity of the measuring light,which has passed through the area of the fine metal particles and thethin metal film, or has been reflected from the area of the fine metalparticles and the thin metal film.

[0080] Effects of the present invention will be described hereinbelow.

[0081] The inventors conducted extensive research and found that theproblems, which are encountered with the conventional technique andwhich the present invention aims at solving as the first objectdescribed above, occur for the reasons described below.

[0082] Specifically, with the conventional sensor chip, each of the finemetal particles, which is loaded within one of the fine holes of thebase body, such as the anodic oxidation alumina, is formed in a tightlyloaded state (i.e., such that no space is present between the fine metalparticle and the peripheral wall of the fine hole. Therefore, thesensing medium is fixed to only the surface area of the fine metalparticle, which surface area stands facing the inlet side of the finehole, and the amount of the sensing medium fixed to the fine metalparticle is markedly small. Accordingly, the change in refractive indexat the peripheral area of the fine metal particle, which change occursdue to the binding of the sensing medium with the specific substance, issmall, and a large change in sensor output signal cannot be obtained.

[0083] Also, with the conventional sensor chip, each of the fine metalparticles is fixed to the bottom of one of the deep fine holes of thebase body, and therefore the sensing medium fixed to the fine metalparticle is present at the deep position in the fine hole. Therefore,the specific substance is capable of binding with the sensing mediumonly after the specific substance has diffused within the fine hole tothe position in the vicinity of the bottom of the fine hole. However, along period of time is required for the specific substance to diffusewithin the fine hole to the position in the vicinity of the bottom ofthe fine hole. Accordingly, a long period of time is required before thechange in sensor output signal is found.

[0084] With the first sensor chip in accordance with the presentinvention, in accordance with the newly obtained findings describedabove, at least a part of each of the fine metal particles is exposed tothe side of the layer-shaped base body, which side is more outward thanthe one surface of the layer-shaped base body. Therefore, the sensingmedium is capable of being fixed to side surface areas, and the like, ofeach of the fine metal particles. Accordingly, the amount of the sensingmedium fixed to each of the fine metal particles becomes large, and thechange in refractive index at the peripheral area of each of the finemetal particles, which change occurs due to the binding of the sensingmedium with the specific substance, becomes large. As a result, a largechange in sensor output signal is capable of being obtained. Therefore,with the first sensor chip in accordance with the present invention, anaccurate analysis is capable of being performed.

[0085] Also, with the first sensor chip in accordance with the presentinvention, wherein each of the fine metal particles, to which thesensing medium is fixed, is located in the state described above, thespecific substance need not diffuse within the fine hole to the positionin the vicinity of the bottom of the fine hole and is capable of bindingwith the sensing medium. Therefore, the change in sensor output signaldue to the binding of the specific substance with the sensing medium iscapable of being found quickly, and the efficiency with which the sampleanalysis is made is capable of being enhanced.

[0086] The anodic oxidation alumina described above is formed as aporous oxide film on the surface of aluminum with processing, whereinaluminum is subjected to anodic oxidation in an acidic electrolyte. Theanodic oxidation alumina has the features such that a plurality ofmarkedly fine holes having diameters ranging from approximately severalnanometers to approximately several hundreds of nanometers are formed asindependent fine holes extending in the direction approximately normalto the surface of the anodic oxidation alumina, and such that the fineholes are formed at approximately equal intervals. Also, the anodicoxidation alumina has the features such that the diameters of the fineholes, the intervals of the fine holes, and the depths of the fine holesare capable of being adjusted comparatively freely by adjustment ofconditions for the anodic oxidation. (The features of the anodicoxidation alumina are described in, for example, Non-Patent Literature 3described above.) During a process for producing the first sensor chipin accordance with the present invention, in order for at least a partof each of the fine metal particles to be exposed to the side of thelayer-shaped base body, which side is more outward than the one surfaceof the layer-shaped base body, the depths of the fine holes of the basebody may be adjusted accurately. Therefore, the anodic oxidation aluminahaving the features described above is markedly appropriate as thematerial for constituting the layer-shaped base body.

[0087] The anodic oxidation alumina described above may be used directlyin the state in which the anodic oxidation alumina has been formed as afilm on the surface of aluminum. Alternatively, the anodic oxidationalumina having been formed on the surface of aluminum may be separatedfrom the surface of aluminum and may then be used in the state in whichthe anodic oxidation alumina has been separated from the surface ofaluminum. As another alternative, the anodic oxidation alumina havingbeen formed on the surface of aluminum may be separated from the surfaceof aluminum and may then be used in a state in which the anodicoxidation alumina has been secured onto a different base plate.

[0088] With the second sensor chip in accordance with the presentinvention, wherein the support member is constituted of the transparentdielectric material having uniform density, optical noise is capable ofbeing prevented from occurring, and measurement with a high sensitivityis capable of being performed.

[0089] With the second sensor chip in accordance with the presentinvention, wherein the transparent dielectric material is constituted ofa polystyrene, in cases where the second sensor chip in accordance withthe present invention is utilized for enzyme immunoassay techniques,such as enzyme-linked immunosorbent assay techniques (ELISA techniques),noise due to non-specific adsorption is capable of being suppressed byvirtue of the characteristics of the polystyrene undergoing littlenon-specific adsorption of proteins. Therefore, measurement with a highsensitivity is capable of being performed.

[0090] With the process for producing a sensor chip in accordance withthe present invention, the fine holes are capable of being located at ahigh density in the support member, which is constituted of thetransparent dielectric material capable of substantially transmittingthe measuring light, and a sensor chip having a high sensitivity iscapable of being obtained. Also, the sizes of the fine metal particlesare capable of being set at arbitrary sizes, and various sensor chipsappropriate for the purposes of use of the sensor chips are capable ofbeing obtained.

[0091] With the second sensor in accordance with the present invention,wherein the second sensor chip in accordance with the present inventionhaving the effects of suppressing optical noise and enabling measurementwith a high sensitivity is used, analysis of a sample is capable ofbeing performed with a high sensitivity.

[0092] The fine structure body in accordance with the present inventioncomprises the layer-shaped base body, which has the plurality of thefine holes formed in one surface, and the fine metal particles, each ofwhich is loaded in one of the fine holes of the base body. Therefore, incases where the fine structure body in accordance with the presentinvention is used as a sensor unit as in the cases of the conventionalsensor described above, in which the localized plasmon resonance isutilized, the refractive index of a sample located at the peripheralareas of the fine metal particles, physical properties of the samplecorresponding to the refractive index, the occurrence of the binding ofa sensing medium, which is located at the peripheral areas of the finemetal particles, with a specific substance, and the like, are capable ofbeing detected.

[0093] Also, the fine structure body in accordance with the presentinvention comprises the thin metal film formed on the areas of the onesurface of the layer-shaped base body, which areas are located aroundeach of the fine holes of the layer-shaped base body, such that the thinmetal film is located at the spacing, which is approximately equal to atmost the diameter of each of the fine metal particles, from each of thefine metal particles. Therefore, near field light, which occurs when themeasuring light is irradiated to an area of the fine metal particles,interacts with the thin metal film, and an absorption spectrum due toelectric multipoles occurs with the measuring light.

[0094] Also, with the fine structure body in accordance with the presentinvention, wherein the layer-shaped base body is transparent withrespect to the light irradiated to the layer-shaped base body, surfaceplasmon resonance is excited by the interaction between the lighttotally reflected within the layer-shaped base body and the thin metalfilm.

[0095] Therefore, in cases where the fine structure body in accordancewith the present invention is used in a sensor utilizing the localizedplasmon resonance, the measuring light absorption and scatteringspectral characteristics alter sufficiently sharply due to thesynergistic effects of the localized plasmon resonance and the electricmultipoles, or the synergistic effects of the localized plasmonresonance, the electric multipoles, and the surface plasmon resonance.The third sensor using the fine structure body in accordance with thepresent invention comprises: (i) the means for irradiating the measuringlight to the area of the fine metal particles and the thin metal film ofthe fine structure body, and (ii) the photo detecting means fordetecting the intensity of the measuring light, which has passed throughthe area of the fine metal particles and the thin metal film, or hasbeen reflected from the area of the fine metal particles and the thinmetal film. Accordingly, with the third sensor using the fine structurebody in accordance with the present invention, a slight change inrefractive index of a sample or physical properties of the sample andslight binding of a specific substance with a sensing medium are capableof being detected.

[0096] As described above, the fine structure body in accordance withthe present invention is capable of being use appropriately in a sensorutilizing the localized plasmon resonance. The fine structure body inaccordance with the present invention is also applicable to a lightmodulating device, wherein light to be modulated is irradiated to thearea of the fine metal particles and the thin metal film, the refractiveindex of a medium located around the area of the fine metal particlesand the thin metal film is caused to alter, and the light to bemodulated is thereby modulated. In cases where the fine structure bodyin accordance with the present invention is applied to the lightmodulating device described above, a large extinction ratio is capableof being obtained in accordance with the slight change in refractiveindex of the medium described above.

[0097] As described above, the anodic oxidation alumina described aboveis formed as a porous oxide film on the surface of aluminum withprocessing, wherein aluminum is subjected to anodic oxidation in anacidic electrolyte. The anodic oxidation alumina has the features suchthat a plurality of markedly fine holes having diameters ranging fromapproximately several nanometers to approximately several hundreds ofnanometers are formed as independent fine holes extending in thedirection approximately normal to the surface of the anodic oxidationalumina, and such that the fine holes are formed at approximately equalintervals. Also, the anodic oxidation alumina has the features such thatthe diameters of the fine holes, the intervals of the fine holes, andthe depths of the fine holes are capable of being adjusted comparativelyfreely by adjustment of conditions for the anodic oxidation. (Thefeatures of the anodic oxidation alumina are described in, for example,Non-Patent Literature 3 described above.) During the process forproducing the fine structure body in accordance with the presentinvention, in order for each of the fine metal particles and and thethin metal film to be located such that the thin metal film is locatedat the spacing, which is approximately equal to at most the diameter ofeach of the fine metal particles, from each of the fine metal particles,the depths of the fine holes of the base body may be adjustedaccurately. Therefore, the anodic oxidation alumina having the featuresdescribed above is markedly appropriate as the material for constitutingthe layer-shaped base body of the fine structure body in accordance withthe present invention.

[0098] The aforesaid anodic oxidation alumina for constituting thelayer-shaped base body of the fine structure body in accordance with thepresent invention may be used directly in the state in which the anodicoxidation alumina has been formed as a film on the surface of aluminum.Alternatively, the anodic oxidation alumina having been formed on thesurface of aluminum may be separated from the surface of aluminum andmay then be used in the state in which the anodic oxidation alumina hasbeen separated from the surface of aluminum. As another alternative, theanodic oxidation alumina having been formed on the surface of aluminummay be separated from the surface of aluminum and may then be used in astate in which the anodic oxidation alumina has been secured onto adifferent base plate.

[0099] With the fine structure body in accordance with the presentinvention, wherein the layer-shaped base body is divided into theplurality of the layer-shaped base sub-bodies, which are located at aspacing from one another and are supported together with one another,each of the layer-shaped base sub-bodies is capable of being dipped into one of wells of a micro-titer plate, which well shave been filledwith different samples. Therefore, the differrent sample shaving beenfilled in the wells of the micro-titer plate are capable of beingsupplied simultaneously to the respective layer-shaped base sub-bodies(i.e., the fine metal particles and the thin metal films, which aresupported by the layer-shaped base sub-bodies) In such cases, theefficiency of the sample supplying operation is capable of beingenhanced. Also, the measuring light is capable of being irradiatedsimultaneously to the layer-shaped base sub-bodies. Alternatively, themeasuring light is capable of being irradiated successively at shorttime intervals to the layer-shaped base sub-bodies. As a result, theefficiency with which the detection of the measuring light is performedis capable of being enhanced. Accordingly, analyses and measurements ofa large number of samples are capable of being performed quickly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0100]FIG. 1 is a schematic side view showing an embodiment of the firstsensor chip in accordance with the present invention,

[0101]FIG. 2 is a side view showing an embodiment of the first sensor inaccordance with the present invention,

[0102]FIG. 3 is a schematic side view showing how the sensor chip ofFIG. 1 is used for sample analysis,

[0103]FIG. 4 is a graph showing spectral intensity characteristics ofmeasuring light detected with the sensor shown in FIG. 3,

[0104]FIG. 5 is a schematic side view showing a different embodiment ofthe first sensor chip in accordance with the present invention,

[0105]FIG. 6 is a schematic side view showing a further differentembodiment of the first sensor chip in accordance with the presentinvention,

[0106]FIG. 7 is a schematic side view showing a different embodiment ofthe first sensor in accordance with the present invention,

[0107]FIG. 8 is a schematic side view showing a still further differentembodiment of the first sensor chip in accordance with the presentinvention,

[0108]FIG. 9 is a perspective view showing an embodiment of the secondsensor chip in accordance with the present invention,

[0109]FIGS. 10A to 10E are sectional views showing how the second sensorchip in accordance with the present invention is produced,

[0110]FIG. 11 is a schematic view showing an embodiment of the secondsensor in accordance with the present invention, which is constituted asa reflection type of sensor,

[0111]FIG. 12 is a graph showing the relationship between wavelengths ofreflected light and intensity of the reflected light at the time oflocalized plasmon resonance,

[0112]FIG. 13 is a schematic view showing a different embodiment of thesecond sensor in accordance with the present invention, which isconstituted as a transmission type of sensor,

[0113]FIG. 14 is a schematic view showing a further different embodimentof the second sensor in accordance with the present invention, which isconstituted as a biosensor,

[0114]FIG. 15 is a partial sectional view showing a state at a surfaceof the second sensor chip in accordance with the present invention,which is used as the biosensor,

[0115]FIG. 16 is a schematic side view showing an embodiment of the finestructure body in accordance with the present invention,

[0116]FIGS. 17A and 17B are schematic views showing an example of howthe fine structure body of FIG. 16 is produced,

[0117]FIGS. 18A, 18B, and 18C are schematic views showing a differentexample of how the fine structure body of FIG. 16 is produced,

[0118]FIG. 19 is a schematic side view showing an embodiment of thethird sensor in accordance with the present invention,

[0119]FIG. 20 is a graph showing spectral intensity characteristics ofmeasuring light detected with the sensor shown in FIG. 19,

[0120]FIG. 21 is a schematic side view showing a different embodiment ofthe fine structure body in accordance with the present invention,

[0121]FIG. 22 is a schematic side view showing a different embodiment ofthe third sensor in accordance with the present invention,

[0122]FIG. 23 is a schematic side view showing a state of the finestructure body of FIG. 21 at the time of sample analysis,

[0123]FIG. 24 is a schematic side view showing a further differentembodiment of the fine structure body in accordance with the presentinvention and a further different embodiment of the third sensor inaccordance with the present invention,

[0124]FIG. 25 is a schematic side view showing a still further differentembodiment of the fine structure body in accordance with the presentinvention and a still further different embodiment of the third sensorin accordance with the present invention, and

[0125]FIG. 26 is a schematic view showing an even further differentembodiment of the fine structure body in accordance with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0126] The present invention will hereinbelow be described in furtherdetail with reference to the accompanying drawings.

[0127]FIG. 1 is a schematic side view showing a sensor chip 10, which isan embodiment of the first sensor chip in accordance with the presentinvention. As illustrated in FIG. 1, the sensor chip 10 comprises analuminum base plate 11. The sensor chip 10 also comprises anodicoxidation alumina 12, which is formed on the aluminum base plate 11 andacts as the layer-shaped base body. The anodic oxidation alumina 12 hasa plurality of fine holes 12 a, 12 a, . . . , which are formed in onesurface (the upper surface in FIG. 1) 12 b. The sensor chip 10 furthercomprises fine gold (Au) particles 13, 13, . . . , each of which isloaded in one of the fine holes 12 a, 12 a, . . .

[0128] In this embodiment of the sensor chip 10, each of the fine goldparticles 13, 13, . . . loaded on the bottoms of the fine holes 12 a, 12a, . . . has a diameter of approximately 200 nm. Each of the fine goldparticles 13, 13, . . . should preferably have a diameter falling withinthe range of, for example, approximately several nanometers toapproximately 100 nm. Also, the depth of each of the fine holes 12 a, 12a, . . . is smaller than the radius of each of the fine gold particles13, 13, . . . Therefore, at least a one-half part of each of the finegold particles 13, 13, . . . is exposed to the side of the anodicoxidation alumina 12, which side is more outward than the one surface 12b of the anodic oxidation alumina 12.

[0129] By way of example, the sensor chip 10 having the constitutiondescribed above may be produced in the manner described below.Specifically, firstly, the aluminum base plate 11 having the surface, onwhich the film of the anodic oxidation alumina 12 has been formed, isprepared. Thereafter, vacuum evaporation processing with gold isperformed on the anodic oxidation alumina 12. The vacuum evaporationprocessing with gold is performed from the side of the one surface 12 bof the anodic oxidation alumina 12, in which surface the fine holes 12a, 12 a, . . . have been formed. With the vacuum evaporation processing,each of the fine gold particles 13, 13, . . . is loaded in one of thefine holes 12 a, 12 a, . . . of the anodic oxidation alumina 12. Thisembodiment of the sensor chip 10 is thus obtained.

[0130] In lieu of the fine gold particles 13, 13, . . . , fine metalparticles of a different metal, e.g. silver, may be formed. However,from the view point described below, gold is particularly preferable asthe material for the formation of the sensor chip in accordance with thepresent invention. Specifically, gold has good malleability and goodductility, and therefore the vacuum evaporation processing with gold iscapable of being performed appropriately at comparatively lowtemperatures. Also, since gold has a high corrosion resistance, in caseswhere the sensor chip 10 provided with the fine gold particles 13, 13, .. . is utilized in a sensor, which will be described later, a sensorhaving stable characteristics is capable of being obtained. Further, thesensor chip 10 provided with the fine gold particles 13, 13, . . . iseasy to process during the production and the use of the sensor.

[0131] Alternatively, the first sensor chip in accordance with thepresent invention, in which the part of each of the fine metal particlesis exposed to the side of the layer-shaped base body, which side is moreoutward than the one surface of the layer-shaped base body, may beproduced in the manner described below. Specifically, firstly, a metal,such as gold or silver, may be loaded in each of the fine holes of theanodic oxidation alumina with vacuum evaporation processing, sputteringprocessing, plating processing, or the like. Thereafter, the metalclinging to the surface of the anodic oxidation alumina may be wiped offand removed by use of an applicator, or the like. In this manner, eachof isolated metal particles is formed in one of the fine holes of theanodic oxidation alumina. Further, the alumina layer may be subjected toetching with a mixed liquid of phosphoric acid (e.g., 6 wt %) andchromic acid (e.g., 1.8 wt %).

[0132] The layer-shaped anodic oxidation alumina 12 may be formed on thealuminum base plate 11 in the manner described below. The layer-shapedanodic oxidation alumina 12 may be formed with one of varioustechniques. Basically, a technique is employed wherein, when thealuminum base plate 11 is subjected to anodic oxidation in an acidicelectrolyte, the formation of an oxide film and the dissolution of theoxide film having been formed are allowed to progress simultaneously.With the technique described above, with the dissolving effect of theacid, fine pits (fine holes) occur at random in the surface of the oxidefilm, which has been formed on the aluminum base plate 11 at the initialstage of the anodic oxidation. Also, as the anodic oxidation progresses,certain pits among the pits described above grow preferentially, and aplurality of pits are thus arrayed at approximately equal intervals inthe surface of the oxide film. An area of the oxide film, at which a pithas been formed, is exerted to an electric field, which is stronger thanthe electric field applied to the other areas of the oxide film.Therefore, the dissolution of the area of the oxide film, at which thepit has been formed, is promoted. As a result, in the layer-shapedanodic oxidation alumina 12, as the layer-shaped anodic oxidationalumina 12 grows, the fine holes 12 a, 12 a, . . . are formed byselective dissolution, and an area, which is not dissolved and remainsin the pattern surrounding each of the fine holes 12 a, 12 a, . . . , isformed.

[0133] In the anodic oxidation alumina 12 obtained in the mannerdescribed above, the plurality of the fine holes 12 a, 12 a, . . . areformed in the regularly arrayed pattern. Each of the fine holes 12 a, 12a, . . . constitutes a space, which extends in the directionapproximately normal to the surface of the anodic oxidation alumina 12.Also, the space constituted by each of the fine holes 12 a, 12 a, . . .has an approximately identical cross-sectional shape and a closedbottom.

[0134] Techniques for regulating the positions, at which the fine holesare formed, are disclosed in, for example, Japanese Unexamined PatentPublication Nos. 2001-9800 and 2001-138300. With the disclosedtechniques for regulating the positions, at which the fine holes areformed, for example, a converged ion beam is irradiated to aluminum, anddissolution start points are thereby formed at desired positions on thealuminum. Thereafter, the anodic oxidation processing is performed inthe manner described above. In this manner, the fine holes 12 a, 12 a, .. . are capable of being formed at the desired positions. Also, by theadjustment of the conditions at the time of the irradiation of theconverged ion beam, such as the quantity of irradiation of the convergedion beam, the diameter of the converged ion beam, and the irradiationenergy, the recess shapes and compositions of the dissolution startpoints are capable of being altered. Therefore, the diameters of thefinally formed fine holes 12 a, 12 a, . . . are capable of beingregulated freely.

[0135] Further, as a technique for forming the array of the fine holes12 a, 12 a, . . . at a particularly high density, for example, atechnique wherein oxalic acid is used may be employed. Specifically,oxalic acid may be utilized as the electrolyte for the anodic oxidation,and the anodic oxidation processing may be performed at a predeterminedvoltage of approximately 40V. In such cases, the fine holes 12 a, 12 a,. . . are capable of being formed in a regularly arrayed pattern and ata high density. The regularity of the array of the fine holes 12 a, 12a, . . . progresses with the passage of time of anodic oxidation.Therefore, in cases where the anodic oxidation processing is performedfor a long period of time, the fine holes 12 a, 12 a, . . . , which arelocated at a high regularity and at a high density, are capable of beingformed.

[0136] In the manner described above, the diameters, the intervals, andthe depths of the fine holes 12 a, 12 a, . . . are capable of beingregulated comparatively freely. Therefore, the fine gold particles 13,13, . . . are capable of being formed with arbitrary uniform size andare capable of being located regularly. As a result, in cases where thesensor chip 10 is used in the sensor, which will be described later, thesensitivity of the sensor is capable of being enhanced and kept stable.

[0137] An embodiment of the first sensor in accordance with the presentinvention will be described hereinbelow. FIG. 2 is a side view showingan embodiment of the first sensor in accordance with the presentinvention, which is constituted as a biosensor using the sensor chip 10described above. FIG. 3 is an enlarged view showing the part of thesensor chip 10 in the sensor of FIG. 2. As illustrated in FIG. 2, thesensor comprises a vessel 20 having a transparent window 22, which isformed at the top surface of the vessel 20. The sensor chip 10 issecured to the inside bottom surface of the vessel 20. The sensor alsocomprises a white light source 24 for irradiating measuring light 23obliquely toward the sensor chip 10 secured to the inside bottom surfaceof the vessel 20. The sensor further comprises a spectrophotometer 25for spectrophotometrically detecting the measuring light 23, which hasbeen reflected from the sensor chip 10. The sensor still furthercomprises displaying means 26 for displaying the results of thespectrophotometric detection.

[0138] Before the sensor chip 10 is used in the sensor, an antibody 31(indicated by the Y-shaped mark in FIG. 3) acting as a sensing medium isfixed to the part of each of the fine gold particles 13, 13, . . . ofthe sensor chip 10, which part is exposed to the side of the anodicoxidation alumina 12 more outward than the one surface of the anodicoxidation alumina 12. The sensor chip 10 is located within the vessel 20such that the one surface of the anodic oxidation alumina 12, in whichsurface the fine gold particles 13, 13, . . . have been loaded, standsfacing up. Also, a sample liquid 30 to be analyzed is introduced intothe vessel 20 such that the sample liquid 30 comes into contact with theanodic oxidation alumina 12.

[0139] The measuring light 23, which is white light, is irradiatedthrough the transparent window 22 of the vessel 20 to the sensor chip10, which has been located within the vessel 20 in the manner describedabove. In such cases, the measuring light 23 is reflected from theirradiated area of the fine gold particles 13, 13, . . . (illustrated inFIGS. 1 and 3). The measuring light 23 having thus been reflected fromthe irradiated area of the fine gold particles 13, 13, . . . isspectrophotometrically detected by the spectrophotometer 25. Also, insuch cases, the measuring light 23 passes through the area of the anodicoxidation alumina 12, at which area the fine gold particles 13, 13, . .. are present. The measuring light 23 having passed through theaforesaid area of the anodic oxidation alumina 12 is reflected upwardlyfrom the aluminum base plate 11. The measuring light 23 having thus beenreflected upwardly from the aluminum base plate 11 is alsospectrophotometrically detected by the spectrophotometer 25.

[0140] The reflected light, which is thus detected, has the spectralintensity characteristics basically identical with the spectralintensity characteristics illustrated in FIG. 4. Specifically, in caseswhere the measuring light 23 is irradiated to the area of the fine goldparticles 13, 13, . . . of the anodic oxidation alumina 12, as for alight component having a specific wavelength λ_(LP), the scattering andthe absorption of the measuring light increase specifically due to thelocalized plasmon resonance. Therefore, as for the light componenthaving the specific wavelength λ_(LP), the intensity of the reflectedlight becomes markedly low.

[0141] At this time, as illustrated in FIG. 3, in cases where a specificantigen 32, which is capable of undergoing specific binding with theantibody 31 described above, is contained in the sample liquid 30, theantigen 32 is bound to the antibody 31 of the sensor chip 10. In caseswhere the antigen 32 is thus bound to the antibody 31, the refractiveindex at the peripheral areas of the fine gold particles 13, 13, . . .of the sensor chip 10 changes. As a result, the absorption andscattering spectral characteristics of the measuring light 23 detectedby the spectrophotometer 25 change. By way of example, in cases where aresonance peak wavelength is λ_(LP) 1 as indicated by the broken line inFIG. 4 before the binding of the antibody 31 with the antigen 32 arises,the resonance peak wavelength changes to λ_(LP) 2 as indicated by thesolid line in FIG. 4 after the binding of the antibody 31 with theantigen 32 arises. As described above, the change in absorption andscattering spectral characteristics of the measuring light 23 detectedby the spectrophotometer 25 appears as a shift of the resonance peakwavelength. Therefore, the absorption and scattering spectralcharacteristics of the measuring light 23 may be detected by thespectrophotometer 25 before the sample liquid 30 is introduced into thevessel 20 and after the sample liquid 30 is introduced into the vessel20. Also, the results of the detection may be displayed on thedisplaying means 26. In this manner, from the change in displayedresonance peak wavelength, it is possible to find whether the binding ofthe antibody 31 with the antigen 32 has or has not occurred, i.e.whether the antigen 32 is or is not present in the sample liquid 30.

[0142] The sensor chip 10 used in the sensor is constituted such thatthe part of each of the fine gold particles 13, 13, . . . of the sensorchip 10 is exposed to the side of the anodic oxidation alumina 12, whichside is more outward than the one surface 12 b of the anodic oxidationalumina 12. Therefore, the advantages over the cases, wherein fine metalparticles are fixed to bottoms of deep fine holes, are capable of beingobtained in that the antibody 31 is capable of being fixed to sidesurface areas, and the like, of each of the fine gold particles 13, 13,. . . Accordingly, the amount of the antibody 31 fixed to each of thefine gold particles 13, 13, . . . becomes large, and the change inrefractive index at the peripheral area of each of the fine goldparticles 13, 13, . . . , which change occurs due to the binding of theantibody 31 with the antigen 32, becomes large. As a result, a largechange in sensor output signal is capable of being obtained. Therefore,with the sensor chip 10, an accurate analysis is capable of beingperformed.

[0143] Also, with the sensor chip 10, wherein each of the fine goldparticles 13, 13, . . . , to which the antibody 31 is fixed, is locatedin the state described above, the advantages over the cases, wherein thefine metal particles are fixed to the bottoms of the deep fine holes,are capable of being obtained in that the antigen 32 need not diffusewithin the fine hole to the position in the vicinity of the bottom ofthe fine hole and is capable of binding with the antibody 31. Therefore,the change in sensor output signal due to the binding of the antigen 32with the antibody 31 is capable of being found quickly, and theefficiency with which the sample analysis is made is capable of beingenhanced.

[0144] The characteristics illustrated in FIG. 4 are capable of beingdetermined previously in accordance with experience or experiments.

[0145] In the embodiment described above, the measuring light 23, whichis the white light and has been reflected from the sensor chip 10, isdetected spectrophotometrically, and the resonance peak wavelengthλ_(LP) is thereby detected. Alternatively, monochromatic light may beemployed as the measuring light, and the shift of the resonance peakwavelength λ_(LP) or the change in light intensity accompanying thechange in scattering and absorption of the measuring light 23 may bedetected. In such cases, the occurrence of the binding of the antibody31 with the antigen 32 is capable of being detected.

[0146] More specifically, examples of the combinations of the antibody31 and the antigen 32 include a combination of biotin and streptoavidin,and the like. In such cases, in order for biotin to be fixed more firmlyto the sensor chip 10, the surface of the anodic oxidation alumina 12should preferably be modified with a self-assembled monolayer. Theself-assembled monolayer of this type is described in detail in, forexample, “Modeling Organic Surfaces with Self-Assembled Monolayers” byColin D. Brain and George M. Whitesides, Angewandte Chemie InternationalEdition in English, Vol. 28, No. 4, pp. 506-512, 1989.

[0147] A sensor chip 40, which is a different embodiment of the firstsensor chip in accordance with the present invention, will be describedhereinbelow with reference to FIG. 5. The sensor chip 40 is constitutedbasically in the same manner as that for the sensor chip 10 of FIG. 1,except that only a part of the surface of each of the fine goldparticles 13, 13, . . . is exposed to the side of the anodic oxidationalumina 12, which side is more outward than the one surface 12 b of theanodic oxidation alumina 12. In FIG. 5 (and those that follow), similarelements are numbered with the same reference numerals with respect toFIG. 1.

[0148] With the sensor chip 40 constituted in the manner describedabove, the part of the surface of each of the fine gold particles 13,13, . . . is exposed to the side of the anodic oxidation alumina 12,which side is more outward than the one surface 12 b of the anodicoxidation alumina 12. Therefore, as in the cases of the sensor chip 10of FIG. 1, an accurate analysis is capable of being performed, and theefficiency with which the sample analysis is made is capable of beingenhanced.

[0149] A sensor chip 50, which is a further different embodiment of thefirst sensor chip in accordance with the present invention, will bedescribed hereinbelow with reference to FIG. 6. The sensor chip 50 isconstituted basically in the same manner as that for the sensor chip 10of FIG. 1, except that the thickness of anodic oxidation alumina 12′ ofthe sensor chip 50 is larger than the thickness of the anodic oxidationalumina 12 of the sensor chip 10, and the anodic oxidation alumina 12′having fine holes 12 a′, 12 a′, . . . is used in the state in which theanodic oxidation alumina 12′ has been separated from the aluminum baseplate 11 illustrated in FIG. 1. In this manner, the sensor chip 50 isconstituted of the anodic oxidation alumina 12′ acting as the unit body.Alternatively, the anodic oxidation alumina 12′ may be secured to adifferent transparent member having a high rigidity, and a sensor chipcomprising the anodic oxidation alumina 12′ and the transparent membermay thus be constituted.

[0150] The sensor chip 50 is used in order to constitute a biosensorillustrated in FIG. 7. The biosensor illustrated in FIG. 7 comprises thesensor chip 50, a vessel 20′, the white light source 24, and thespectrophotometer 25. In this embodiment, the vessel 20′ is providedwith transparent windows 22′, 22′, which are formed at the side surfacesthat stand facing each other. Also, the white light source 24 is locatedin an orientation such that the measuring light 23, which is the whitelight, enters through one of the transparent windows 22′, 22′ into thevessel 20′. Further, the spectrophotometer 25 is located in anorientation such that the spectrophotometer 25 receives the measuringlight 23, which has passed through the vessel 20′ and is radiated outfrom the other transparent window 22′. Furthermore, the sensor chip 50is located at the position such that the sensor chip 50 enters into theoptical path of the measuring light 23 within the vessel 20′.

[0151] In the embodiment of the sensor illustrated in FIG. 7, the sampleliquid 30 to be analyzed is introduced into the vessel 20′. Also, themeasuring light 23 traveling within the vessel 20′ passes through thearea of the fine gold particles 13, 13, . . . of the sensor chip 50,which particles are in contact with the sample liquid 30. The measuringlight 23 having passed through the area of the fine gold particles 13,13, . . . of the sensor chip 50 is detected by the spectrophotometer 25.Therefore, with this embodiment of the sensor, as in the cases of thesensor illustrated in FIG. 2, the occurrence of the binding of theantibody 31 and the antigen 32 is capable of being detected. Also, withthis embodiment of the sensor chip 50, the part of the surface of eachof the fine gold particles 13, 13, . . . is exposed to the side of theanodic oxidation alumina 12′, which side is more outward than the onesurface 12 b of the anodic oxidation alumina 12′. Therefore, an accurateanalysis is capable of being performed, and the efficiency with whichthe sample analysis is made is capable of being enhanced.

[0152] A sensor chip 60, which is a still further different embodimentof the first sensor chip in accordance with the present invention, willbe described hereinbelow with reference to FIG. 8. The sensor chip 60 isconstituted basically in the same manner as that for the sensor chip 50of FIG. 6, except that only a part of the surface of each of the finegold particles 13, 13, . . . is exposed to the side of the anodicoxidation alumina 12′, which side is more outward than the one surface12 b of the anodic oxidation alumina 12′.

[0153] The sensor chip 60 is capable of being used in order toconstitute the transmission type of the sensor illustrated in FIG. 7.Also, with the sensor chip 60 constituted in the manner described above,the part of the surface of each of the fine gold particles 13, 13, . . .is exposed to the side of the anodic oxidation alumina 12′, which sideis more outward than the one surface 12 b of the anodic oxidationalumina 12′. Therefore, as in the cases of the sensor chip 50 of FIG. 6,an accurate analysis is capable of being performed, and the efficiencywith which the sample analysis is made is capable of being enhanced.

[0154] In the process for producing the sensor chip 50 illustrated inFIG. 6 or the sensor chip 60 illustrated in FIG. 8, the aluminum baseplate, on which the anodic oxidation alumina 12′ has been formed, isremoved from the anodic oxidation alumina 12′. For this purpose, forexample, a technique, wherein the aluminum base plate is subjected toetching processing using a saturated HgCl₂ solution or an acid, such assulfuric acid, may be employed. The aforesaid technique for the etchingprocessing is described in, for example, Japanese Journal of AppliedPhysics, Vol. 37, pp. L1090-1092, 1998.

[0155] An embodiment of the second sensor chip in accordance with thepresent invention will be described hereinbelow with reference to FIG.9. FIG. 9 is a perspective view showing an embodiment of the secondsensor chip in accordance with the present invention.

[0156] With reference to FIG. 9, a sensor chip 110 comprises a supportmember 111, which is constituted of a polystyrene. The support member111 has a plurality of independent fine holes 111 b, 111 b, . . . ,which extend in a direction approximately normal to a surface 111 a ofthe support member 111. The sensor chip 110 also comprises independentfine gold (Au) particles 113 a, 113 a, . . . , each of which issupported within one of the fine holes 111 b, 111 b, . . . of thesupport member 111.

[0157] As illustrated in FIG. 9, the fine holes 111 b, 111 b, . . . arearrayed regularly. Each of the fine gold particles 113 a, 113 a, . . .loaded on the bottoms of the fine holes 111 b, 111 b, . . . has adiameter falling within the range of, for example, approximately severalnanometers to approximately 200 nm. Also, the depth of each of the fineholes 111 b, 111 b, . . . may be set at an arbitrary value.

[0158] In this embodiment of the sensor chip 110, gold (Au) is employedas the fine gold particles 113 a, 113 a, . . . Gold constituting thefine gold particles 113 a, 113 a, . . . acting as the fine metalparticles is a good electrical conductor and has good malleability andgood ductility, and therefore the vacuum evaporation processing withgold is capable of being performed appropriately at comparatively lowtemperatures. Also, since gold has a high corrosion resistance, in caseswhere the sensor chip 110 provided with the fine gold particles 113 a,113 a, . . . is utilized in asensor, which will be described later, asensor having stable characteristics is capable of being obtained.Further, the sensor chip 110 provided with the fine gold particles 113a, 113 a, . . . is easy to process during the production and the use ofthe sensor.

[0159] In lieu of the fine gold particles 113 a, 113 a, fine metalparticles constituted of silver or one of other metals may be employed.In particular, in cases where the fine metal particles are constitutedof silver, the sensitivity of the sensor using the sensor chip iscapable of being enhanced.

[0160] In this embodiment of the sensor chip 110, the diameter of eachof the fine gold particles 113 a, 113 a, . . . is set to be smaller thanthe depth of each of the fine holes 111 b, 111 b, . . . , and each ofthe fine gold particles 113 a, 113 a, is supported at a part of theregion within each of the fine holes 111 b, 111 b, . . . .Alternatively, gold may be loaded over the entire area of each of thefine holes 111 b, 111 b, . . .

[0161] In this embodiment of the sensor chip 110, the support member 111is constituted of the polystyrene having uniform density. Therefore,with sensor chip 110, the occurrence of optical noise is capable ofbeing suppressed, and the signal-to-noise ratio is capable of beingenhanced. As a result, measurement with a high sensitivity is capable ofbeing performed.

[0162] In this embodiment of the sensor chip 110, the support member 111is constituted of the polystyrene acting as the transparent dielectricmaterial. In lieu of the polystyrene, a high-molecular weight resin,such as a polymethyl methacrylate (PMMA), may be employed as thetransparent dielectric material for constituting the support member 111.

[0163] An embodiment of the process for producing the second sensor chipin accordance with the present invention will be described hereinbelow.FIGS. 10A to 10E are sectional views showing how the second sensor chipin accordance with the present invention is produced.

[0164] Specifically, firstly, as illustrated in FIG. 10A, an anodicoxidation alumina film 112 is formed on a polystyrene base plate 111.

[0165] The anodic oxidation alumina film 112 may be formed on thepolystyrene base plate 111 in the manner described below. The anodicoxidation alumina film 112 may be formed with one of various techniques.Basically, a technique is employed wherein, when aluminum having beenformed on the polystyrene base plate 111 is subjected to anodicoxidation in an acidic electrolyte, the formation of anoxide film andthe dissolution of the oxide film having been formed are allowed toprogress simultaneously. With the technique described above, with thedissolving effect of the acid, fine pits (fine holes) occur at random inthe surface of the oxide film, which has been formed on the aluminum atthe initial stage of the anodic oxidation. Also, as the anodic oxidationprogresses, certain pits among the pits described above growpreferentially, and a plurality of pits are thus arrayed atapproximately equal intervals in the surface of the oxide film. An areaof the oxide film, at which a pit has been formed, is exerted to anelectric field, which is stronger than the electric field applied to theother areas of the oxide film. Therefore, the dissolution of the area ofthe oxide film, at which the pit has been formed, is promoted. As aresult, in the oxide layer on anode, as the oxide layer grows, the fineholes are formed by selective dissolution, and a wall area, which is notdissolved and remains in the pattern surrounding each of the fine holes,is formed.

[0166] As illustrated in FIG. 10A, in the anodic oxidation alumina film112 obtained in the manner described above, a plurality of first fineholes 112 a, 112 a, . . . are formed in a regularly arrayed pattern onthe surface 111 a of the polystyrene base plate 111. Each of the firstfine holes 112 a, 112 a, . . . constitutes a circular cylinder-shapedspace, which extends in the direction approximately normal to the layersurface of the anodic oxidation alumina film 112 having been formed andhas an approximately identical cross-sectional shape.

[0167] The anodic oxidation alumina film 112 may be formed with theprocessing, wherein an aluminum film is formed on the surface 111 a ofthe polystyrene base plate 111 in the manner described above and is thensubjected to the anodic oxidation. Alternatively, the anodic oxidationalumina film 112 may be formed previously and may then be laminated withthe polystyrene base plate 111.

[0168] Thereafter, as illustrated in FIG. 10B, the polystyrene baseplate 111 is subjected to etching processing, in which the anodicoxidation alumina film 112 having been formed on the surface 111 a ofthe polystyrene base plate 111 is utilized as a mask. In this manner, aplurality of the second fine holes 111 b, 111 b, . . . , each of whichcorresponds to one of the first fine holes 112 a, 112 a, . . . , areformed in the surface 111 a of the polystyrene base plate 111. Theetching processing may be performed by use of an etchant, such as oxygenor CF₄.

[0169] Thereafter, as illustrated in FIG. 10C, the anodic oxidationalumina film 112 is removed from the surface 111 a of the polystyrenebase plate 111.

[0170] Thereafter, as illustrated in FIG. 10D, a gold depositingoperation, such as a vacuum evaporation operation with gold or asputtering operation with gold, is performed on the polystyrene baseplate 111 having the surface 111 a, in which the second fine holes 111b, 111 b, . . . have been formed. The gold depositing operation isperformed from the side of the surface 111 a of the polystyrene baseplate 111. With the gold depositing operation, each of the fine goldparticles 113 a, 113 a, . . . is formed within one of the second fineholes 111 b, 111 b, . . . Also, a gold deposit layer 113 b is formed onthe surface 111 a of the polystyrene base plate 111.

[0171] Thereafter, as illustrated in FIG. 10E, only the metal depositlayer 113 b having formed on the surface 111 a of the polystyrene baseplate 111 is removed from the surface 111 a of the polystyrene baseplate 111. In this manner, each of independent fine gold particles 113a, 113 a, . . . is capable of being supported within one of the secondfine holes 111 b, 111 b, . . . The metal deposit layer 113 b having beenformed on the surface 111 a of the polystyrene base plate 111 is capableof being easily scraped off by use of an applicator. Alternatively, themetal deposit layer 113 b may be removed with a polishing operationusing a file, or the like.

[0172] As for techniques for regulating the fine holes, techniques forforming start points of fine hole formation are disclosed in, forexample, Japanese Unexamined Patent Publication Nos. 2001-9800 and2001-138300. Specifically, the start points of fine hole formation areformed at desired positions on the site of a workpiece containingaluminum as a principal constituent. Thereafter, the workpiece issubjected to the anodic oxidation processing. In this manner, the fineholes are capable of being formed at the desired positions. Therefore,the array of the fine holes of a nano-structure, the intervals of thefine holes, the positions of the fine holes, the orientation of the fineholes, and the like, are capable of being regulated. As the techniquefor forming the start points of fine hole formation, the conditions atthe time of the irradiation of the converged ion beam, such as thequantity of irradiation of the converged ion beam, the diameter of theconverged ion beam, and the irradiation energy, may be adjusted. In thismanner, the recess shapes and compositions of the fine hole start pointsare capable of being regulated. Therefore, the fine hole diameters ofthe finally formed nanoholes are capable of being regulated.

[0173] Further, as a technique for forming the array of the fine holesat a particularly high density, for example, a technique wherein oxalicacid is used may be employed. Specifically, oxalic acid may be utilizedas the electrolyte for the anodic oxidation, and the anodic oxidationprocessing may be performed at a predetermined voltage of approximately40V. In such cases, the fine holes are capable of being formed in aregularly arrayed pattern and at a high density. The regularity of thearray of the fine holes progresses with the passage of time of anodicoxidation. Therefore, in cases where the anodic oxidation processing isperformed for a long period of time, the fine holes are capable of beingformed in an approximately ideal array pattern. Accordingly, the arrayof the fine holes formed in the anodic oxidation alumina film takes amarkedly high regularity which is exceptional for structures formednaturally.

[0174] As described above, with the embodiment of the process forproducing the second sensor chip in accordance with the presentinvention, the polystyrene base plate 111 is subjected to the etchingprocessing, in which the anodic oxidation alumina film 112 having theregularly arrayed first fine holes 112 a, 112 a, . . . is utilized asthe mask. In this manner, the plurality of the second fine holes 111 b,111 b, . . . are formed in the surface 111 a of the polystyrene baseplate 111. Therefore, the fine holes 111 b, 111 b, . . . are capable ofbeing arrayed at a high density. Also, the fine gold particles 113 a,113 a, . . . are capable of being formed such that the fine goldparticles 113 a, 113 a, . . . have uniform size. Further, the sizes ofthe fine gold particles 113 a, 113 a, . . . are capable of being set atan arbitrary value. Accordingly, various sensor chips appropriate forvarious purposes of use are capable of being obtained.

[0175] Furthermore, with the aforesaid embodiment of the process forproducing the second sensor chip in accordance with the presentinvention, a mask having been obtained from fine patterning with alithographic technique, or the like, or an electron beam drawingtechnique, which requires a high cost and has a low productivity, neednot be utilized, and a sensor chip having the fine metal particlesarrayed at a high density is capable of being obtained easily.

[0176] An embodiment of the second sensor in accordance with the presentinvention, wherein the second sensor chip in accordance with the presentinvention is used, will be described hereinbelow. FIG. 11 is a schematicview showing an embodiment of the second sensor in accordance with thepresent invention, which is constituted as a reflection type of sensor.

[0177] As illustrated in FIG. 11, the embodiment of the second sensor inaccordance with the present invention comprises the sensor chip 110 inaccordance with the present invention. The sensor also comprises a lightsource 121 for irradiating measuring light 122 from the side of openingsof the fine holes 111 b, 111 b, . . . to the sensor chip 110, such thatthe measuring light 122 impinges at an oblique angle upon an area of thefine gold particles 113 a, 113 a, . . . The sensor further comprises apolychromator 123, which acts as the photo detecting means for measuringthe intensity of the light having been reflected from the sensor chip.

[0178] The size of each of the fine gold particles 113 a, 113 a, . . .having been supported within the fine holes 111 b, 111 b, . . . , whichsize is taken in the diameter direction of the fine hole, and the sizeof each of the fine gold particles 113 a, 113 a, . . . , which size istaken in the depth direction of the fine hole, are approximatelyidentical with each other. Therefore, the electric field direction ofthe incident light may be parallel with the plane of the sheet of FIG.11 or may be normal to the plane of the sheet of FIG. 11. In cases whereeach of the fine gold particles having been supported within the secondfine holes 111 b, 111 b, . . . takes a rod-like shape, in which thelength of the fine gold particle is larger than the diameter of the finegold particle, the electric field direction of the measuring lightshould preferably be parallel with the plane of the sheet of FIG. 11.

[0179] The measuring light 122 having been produced by the light source121 impinges upon the area of the fine gold particles 113 a, 113 a, . .. of the sensor chip 110 and is reflected from the area of the fine goldparticles 113 a, 113 a, . . . of the sensor chip 110. The intensity ofthe measuring light 122 having thus been reflected from the area of thefine gold particles 113 a, 113 a, . . . is detected by the photodetecting means, which may be constituted of the polychromator 123, orthe like.

[0180]FIG. 12 is a graph showing the relationship between wavelengths ofreflected light and intensity of the reflected light at the time oflocalized plasmon resonance.

[0181] Specifically, in cases where the measuring light 122 isirradiated to the area of the fine gold particles 113 a, 113 a, . . . ofthe sensor chip 110, as for a light component having a specificwavelength λ_(LP), the scattering and the absorption of the measuringlight 122 increase specifically due to the localized plasmon resonance.Therefore, as for the light component having the specific wavelengthλ_(LP), the intensity of the reflected light becomes markedly low. Also,the wavelength (the resonance peak wavelength) λ_(LP), at which thelocalized plasmon resonance occurs, and the extent of the scattering andthe absorption of the measuring light 122 depend upon the refractiveindex of the sample, which is present at the peripheral areas of thefine gold particles 113 a, 113 a, . . . More specifically, as therefractive index of the sample, which is present at the peripheral areasof the fine gold particles 113 a, 113 a, . . . , becomes large, theresonance peak wavelength λ_(LP) shifts to the long wavelength side.Therefore, in cases where the resonance peak wavelength λ_(LP) isdetected, the refractive index of the sample, which is present in thevicinity of the fine gold particles 113 a, 113 a, . . . , the physicalproperties of the sample corresponding to the refractive index, and thelike, are capable of being measured. The refractive index of the sample,which is present in the vicinity of the fine gold particles 113 a, 113a, . . . , and the physical properties of the sample corresponding tothe refractive index, are capable of being calculated by use of a signalprocessing section.

[0182] In this embodiment of the second sensor in accordance with thepresent invention, the intensity of the reflected light is measured.Alternatively, as illustrated in FIG. 13, the second sensor inaccordance with the present invention may be constituted as atransmission type of sensor. In the different embodiment of the secondsensor illustrated in FIG. 13, the measuring light 122 having beenproduced by the light source 121 is irradiated from the side of thesurface lila of the sensor chip 110, which surface is provided with thefine holes 111 b, 111 b, . . . The measuring light 122 is irradiatedfrom the direction normal to the surface 111a of the sensor chip 110.Also, the intensity of the measuring light 122 having passed through thesensor chip 110 is detected by the polychromator 123 acting the photodetecting means. As another alternative, the measuring light 122 havingbeen produced by the light source 121 may be irradiated from a directionother than the direction normal to the surface 111 a of the sensor chip110, which surface is provided with the fine holes 111 b, 111 b, . . .

[0183] Also, white light may be employed as the measuring light 122, andthe measuring light 122 having been reflected from the sensor chip 110or having passed through the sensor chip 110, may be detectedspectrophotometrically. In this manner, the resonance peak wavelengthλ_(LP) may be detected. Alternatively, monochromatic light may beemployed as the measuring light 122, and the shift of the resonance peakwavelength λ_(LP) or the change in light intensity accompanying thechange in scattering and absorption of the measuring light 122 may bedetected. In such cases, the refractive index of the sample, thephysical properties of the sample, and the like, are capable of beingmeasured.

[0184] A further different embodiment of the second sensor in accordancewith the present invention, wherein the second sensor chip in accordancewith the present invention is used, will be described hereinbelow. FIG.14 is a schematic view showing a further different embodiment of thesecond sensor in accordance with the present invention, which isconstituted as a biosensor.

[0185] As illustrated in FIG. 14, the biosensor comprises the sensorchip 110 in accordance with the present invention. The biosensor alsocomprises a vessel 134 having a transparent window 136, which is formedat the top surface of the vessel 134. The sensor chip 110 is secured tothe inside bottom surface of the vessel 134. The biosensor furthercomprises a light source 131 for irradiating white light (measuringlight) 132 to the sensor chip 110 secured to the inside bottom surfaceof the vessel 134. The biosensor still further comprises a polychromator133 for spectrophotometrically detecting the measuring light 132, whichhas been reflected from the sensor chip 110. The sensor chip 110 islocated in the vessel 134 in an orientation such that the surface 111 aof the sensor chip 110, which surface is provided with the fine holes111 b,111 b, . . . , stands facing up.

[0186] As illustrated in FIG. 15, by way of example, an antibody 138(indicated by the Y-shaped mark in FIG. 15) has been fixed to thesurface of each of the fine gold particles 113 a, 113 a, . . . of thesensor chip 110. Also, a sample liquid 135 to be analyzed is introducedinto the vessel 134 such that the sample liquid 135 comes into contactwith the sensor chip 110. The sample liquid 135 contains a specificantigen 137, which is capable of undergoing specific binding with theantibody 138.

[0187] In cases where the antigen 137 is bound to the antibody 138, therefractive index at the peripheral areas of the fine gold particles 113a, 113 a, . . . of the sensor chip 110 changes. As a result, theabsorption and scattering spectral characteristics of the measuringlight 132 detected by the polychromator 133 change. By way of example,as described above with reference to FIG. 4, the change in absorptionand scattering spectral characteristics of the measuring light 132detected by the polychromator 133 appears as the shift of the resonancepeak wavelength. Therefore, the change in resonance peak wavelength maybe detected by the polychromator 133. In this manner, from the change inresonance peak wavelength, it is possible to find whether the binding ofthe antibody 138 with the antigen 137 has or has not occurred, i.e.whether the antigen 137 is or is not present in the sample liquid 135.

[0188] In this embodiment of the biosensor in accordance with thepresent invention, the sensor chip 110, in which the transparentdielectric material for supporting the fine gold particles 113 a, 113 a,. . . is constituted of the polystyrene, is employed. Therefore,non-specific adsorption of the antigen 137 to the polystyrene base plate111 does not occur. Accordingly, the occurrence of optical noise iscapable ofbeing suppressed, and measurement with a high sensitivity iscapable of being performed.

[0189] Embodiments of the fine structure body in accordance with thepresent invention will be described hereinbelow.

[0190]FIG. 16 is a schematic side view showing a fine structure body210, which is an embodiment of the fine structure body in accordancewith the present invention. As illustrated in FIG. 16, the finestructure body 210 comprises an aluminum base plate 211. The finestructure body 210 also comprises anodic oxidation alumina 212, which isformed on the aluminum base plate 211 and acts as the layer-shaped basebody. The anodic oxidation alumina 212 has a plurality of fine holes 212a, 212 a, . . . , which are formed in one surface (the upper surface inFIG. 16). The fine structure body 210 further comprises fine gold (Au)particles 213, 213, . . . , each of which is loaded in one of the fineholes 212 a, 212 a, . . . . The fine structure body 210 still furthercomprises a thin gold film 214 formed on areas of the one surface of theanodic oxidation alumina 212, which areas are located around each of thefine holes 212 a, 212 a, . . . of the anodic oxidation alumina 212.

[0191] In this embodiment of the fine structure body 210, by way ofexample, each of the fine holes 212 a, 212 a, . . . has a depth of atmost approximately 200 nm. Each of the fine gold particles 213, 213, . .. loaded on the bottoms of the fine holes 212 a, 212 a, . . . has adiameter falling within the range of, for example, approximately severalnanometers to approximately 100 nm. Also, the distance between each ofthe fine gold particles 213, 213, . . . and the thin gold film 214, i.e.the distance between the top end of each of the fine gold particles 213,213, . . . and the bottom end of the thin gold film 214, is set to beequal to at most the diameter of each of the fine gold particles 213,213, . . .

[0192] By way of example, the fine structure body 210 having theconstitution described above may be produced in the manner describedbelow. FIGS. 17A and 17B are schematic views showing an example of howthe fine structure body 210 of FIG. 16 is produced. Specifically,firstly, as illustrated in FIG. 17A, the aluminum base plate 211 havingthe surface, on which the film of the anodic oxidation alumina 212 hasbeen formed, is prepared. Thereafter, vacuum evaporation processing withgold is performed on the anodic oxidation alumina 212. The vacuumevaporation processing with gold is performed from the side of the onesurface of the anodic oxidation alumina 212, in which surface the fineholes 212 a, 212 a, . . . have been formed. With the vacuum evaporationprocessing, as illustrated in FIG. 17B, each of the fine gold particles213, 213, . . . is loaded in one of the fine holes 212 a, 212 a, . . .of the anodic oxidation alumina 212, and the thin gold film 214 isformed on the aforesaid one surface of the anodic oxidation alumina 212.This embodiment of the fine structure body 210 is thus obtained.

[0193] Alternatively, this embodiment of the fine structure body 210 maybe produced in the manner described below. FIGS. 18A, 18B, and 18C areschematic views showing a different example of how the fine structurebody 210 of FIG. 16 is produced. Specifically, firstly, as illustratedin FIG. 18A, the aluminum base plate 211 having the surface, on whichthe film of the anodic oxidation alumina 212 has been formed, isprepared. Thereafter, electrolytic plating processing with gold isperformed on the anodic oxidation alumina 212. The electrolytic platingprocessing with gold is performed from the side of the one surface ofthe anodic oxidation alumina 212, in which surface the fine holes 212 a,212 a, . . . have been formed. With the electrolytic plating processing,as illustrated in FIG. 18B, each of the fine gold particles 213, 213, .. . is loaded in one of the fine holes 212 a, 212 a, . . . of the anodicoxidation alumina 212. In cases where the conditions for theelectrolytic plating processing are adjusted appropriately, theelectrolytic plating processing is capable of being performed such thatgold plating is not effected on the surface area of the anodic oxidationalumina 212, and each of the fine gold particles 213, 213, . . . isloaded only in one of the fine holes 212 a, 212 a, . . . of the anodicoxidation alumina 212.

[0194] Thereafter, the vacuum evaporation processing with gold isperformed on the anodic oxidation alumina 212. The vacuum evaporationprocessing with gold is performed from the side of the one surface ofthe anodic oxidation alumina 212, in which surface the fine holes 212 a,212 a, . . . have been formed. With the vacuum evaporation processing,as illustrated in FIG. 18C, the thin gold film 214 is formed on theaforesaid one surface of the anodic oxidation alumina 212. Thisembodiment of the fine structure body 210 may thus be obtained. In caseswhere the conditions for the vacuum evaporation processing are adjustedappropriately, the vacuum evaporation processing is capable of beingperformed such that the gold is not deposited within each of the finegold particles 213, 213, . . . , and only the thin gold film 214 isformed on the aforesaid one surface of the anodic oxidation alumina 212.

[0195] In lieu of the fine gold particles 213, 213, . . . and the thingold film 214, fine metal particles and a thin metal film of a differentmetal, e.g. silver, may be formed. However, from the view pointdescribed below, gold is particularly preferable as the material for theformation of the fine structure body in accordance with the presentinvention. Specifically, gold has good malleability and good ductility,and therefore the vacuum evaporation processing with gold is capable ofbeing performed appropriately at comparatively low temperatures. Also,since gold has a high corrosion resistance, in cases where the finestructure body 210 provided with the fine gold particles 213, 213, . . .and the thin gold film 214 is utilized in a sensor, which will bedescribed later, a sensor having stable characteristics is capable ofbeing obtained. Further, the fine structure body 210 provided with thefine gold particles 213, 213, . . . and the thin gold film 214 is easyto process during the production and the use of the sensor.

[0196] The layer-shaped anodic oxidation alumina 212 may be formed onthe aluminum base plate 211 in the manner described below. Thelayer-shaped anodic oxidation alumina 212 may be formed with one ofvarious techniques. Basically, a technique is employed wherein, when thealuminum base plate 211 is subjected to anodic oxidation in an acidicelectrolyte, the formation of an oxide film and the dissolution of theoxide film having been formed are allowed to progress simultaneously.With the technique described above, with the dissolving effect of theacid, fine pits (fine holes) occur at random in the surface of the oxidefilm, which has been formed on the aluminum base plate 211 at theinitial stage of the anodic oxidation. Also, as the anodic oxidationprogresses, certain pits among the pits described above growpreferentially, and a plurality of pits are thus arrayed atapproximately equal intervals in the surface of the oxide film. An areaof the oxide film, at which a pit has been formed, is exerted to anelectric field, which is stronger than the electric field applied to theother areas of the oxide film. Therefore, the dissolution of the area ofthe oxide film, at which the pit has been formed, is promoted. As aresult, in the layer-shaped anodic oxidation alumina 212, as thelayer-shaped anodic oxidation alumina 212 grows, the fine holes 212 a,212 a, . . . are formed by selective dissolution, and an area, which isnot dissolved and remains in the pattern surrounding each of the fineholes 212 a, 212 a, . . . , is formed.

[0197] In the anodic oxidation alumina 212 obtained in the mannerdescribed above, the plurality of the fine holes 212 a, 212 a, . . . areformed in the regularly arrayed pattern. Each of the fine holes 212 a,212 a, . . . constitutes a circular cylinder-shaped space, which extendsin the direction approximately normal to the surface of the anodicoxidation alumina 212. Also, the circular cylinder-shaped spaceconstituted by each of the fine holes 212 a, 212 a, . . . has anapproximately identical cross-sectional shape and a closed bottom.

[0198] Techniques for regulating the positions, at which the fine holesare formed, are disclosed in, for example, Japanese Unexamined PatentPublication Nos. 2001-9800 and 2001-138300. With the disclosedtechniques for regulating the positions, at which the fine holes areformed, for example, a converged ion beam is irradiated to aluminum, anddissolution start points are thereby formed at desired positions on thealuminum. Thereafter, the anodic oxidation processing is performed inthe manner described above. In this manner, the fine holes 212 a, 212 a,. . . are capable of being formed at the desired positions. Also, by theadjustment of the conditions at the time of the irradiation of theconverged ion beam, such as the quantity of irradiation of the convergedion beam, the diameter of the converged ion beam, and the irradiationenergy, the recess shapes and compositions of the dissolution startpoints are capable of being altered. Therefore, the diameters of thefinally formed fine holes 212 a, 212 a, . . . are capable of beingregulated freely.

[0199] Further, as a technique for forming the array of the fine holes212 a, 212 a, . . . at a particularly high density, for example, atechnique wherein oxalic acid is used may be employed. Specifically,oxalic acid may be utilized as the electrolyte for the anodic oxidation,and the anodic oxidation processing may be performed at a predeterminedvoltage of approximately 40V. In such cases, the fine holes 212 a, 212a, . . . are capable of being formed in a regularly arrayed pattern andat a high density. The regularity of the array of the fine holes 212 a,212 a, . . . progresses with the passage of time of anodic oxidation.Therefore, in cases where the anodic oxidation processing is performedfor a long period of time, the fine holes 212 a, 212 a, . . . , whichare located at a high regularity and at a high density, are capable ofbeing formed.

[0200] In the manner described above, the diameters, the intervals, andthe depths of the fine holes 212 a, 212 a, . . . are capable of beingregulated comparatively freely. Therefore, the fine gold particles 213,213, . . . and the thin gold film 214 are capable of being formed witharbitrary uniform size and are capable of being located regularly. As aresult, in cases where the fine structure body 210 is used in thesensor, which will be described later, the sensitivity of the sensor iscapable of being enhanced and kept stable.

[0201] An embodiment of the third sensor in accordance with the presentinvention will be described hereinbelow. FIG. 19 is a side view showingan embodiment of the third sensor in accordance with the presentinvention, wherein the fine structure body 210 described above is used.As illustrated in FIG. 19, the sensor comprises a vessel 220 having atransparent window 222, which is formed at the top surface of the vessel220. The fine structure body 210 is secured to the inside bottom surfaceof the vessel 220. The sensor also comprises a white light source 224for irradiating measuring light 223 obliquely toward the fine structurebody 210 secured to the inside bottom surface of the vessel 220. Thesensor further comprises a spectrophotometer 225 forspectrophotometrically detecting the measuring light 223, which has beenreflected from the fine structure body 210.

[0202] The fine structure body 210 is located within the vessel 220 suchthat the one surface of the anodic oxidation alumina 212, which surfaceis provided with the fine gold particles 213, 213, . . . and the thingold film 214, stands facing up. Also, a sample liquid 221 to beanalyzed is introduced into the vessel 220 such that the sample liquid221 comes into contact with the anodic oxidation alumina 212.

[0203] The measuring light 223, which is the white light, is irradiatedthrough the transparent window 222 of the vessel 220 to the finestructure body 210, which has been located within the vessel 220 in themanner described above. In such cases, the measuring light 223 isreflected from the irradiated area of the fine gold particles 213, 213,. . . and the thin gold film 214 (illustrated in FIG. 16). The measuringlight 223 having thus been reflected from the irradiated area of thefine gold particles 213, 213, . . . and the thin gold film 214 isspectrophotometrically detected by the spectrophotometer 225. Also, insuch cases, the measuring light 223 passes through the area of theanodic oxidation alumina 212, at which area the fine gold particles 213,213, . . . and the thin gold film 214 are present. The measuring light223 having passed through the aforesaid area of the anodic oxidationalumina 212 is reflected upwardly from the aluminum base plate 211. Themeasuring light 223 having thus been reflected upwardly from thealuminum base plate 211 is also spectrophotometrically detected by thespectrophotometer 225.

[0204] The reflected light, which is thus detected, has the spectralintensity characteristics basically identical with the spectralintensity characteristics indicated by the solid line in FIG. 20.Specifically, in cases where the measuring light 223 is irradiated tothe area of the fine gold particles 213, 213, . . . of the anodicoxidation alumina 212, as for a light component having a specificwavelength λ_(LP), the scattering and the absorption of the measuringlight increase specifically due to the localized plasmon resonance.Therefore, as for the light component having the specific wavelengthλ_(LP), the intensity of the reflected light becomes markedly low.

[0205] Also, the wavelength (the resonance peak wavelength) λ_(LP), atwhich the localized plasmon resonance occurs, and the extent of thescattering and the absorption of the measuring light 223 depend upon therefractive index of the sample liquid 221, which is present at theperipheral areas of the fine gold particles 213, 213, . . . Morespecifically, as the refractive index of the sample liquid 221, which ispresent at the peripheral areas of the fine gold particles 213, 213, . .. , becomes large, the resonance peak wavelength λ_(LP) shifts to thelong wavelength side. Therefore, in cases where the measuring light 223is irradiated to the area of the anodic oxidation alumina 212 havingbeen located in the vessel 220 containing the sample liquid 221, and,for example, the resonance peak wavelength λ_(LP) is detected at thistime, the refractive index of the sample liquid 221, which is present inthe vicinity of the fine gold particles 213, 213, . . . , the physicalproperties of the sample liquid 221 corresponding to the refractiveindex, and the like, are capable of being measured.

[0206] Also, in the fine structure body 210 used in the sensor describedabove, the thin gold film 214 is located at the spacing, which isapproximately equal to at most the diameter of each of the fine goldparticles 213, 213, . . . , from each of the fine gold particles 213,213, . . . Therefore, near field light, which occurs when the measuringlight 223 is irradiated to an area of the fine gold particles 213, 213,. . . , interacts with the thin gold film 214, and an absorptionspectrum due to electric multipoles occurs with the measuring light 223.Further, the surface plasmon resonance is excited by the interactionbetween the measuring light 223, which is totally reflected within thetransparent anodic oxidation alumina 212, and the thin gold film 214.

[0207] Therefore, with the sensor described above, the measuring lightabsorption and scattering spectral characteristics alter sharply due tothe synergistic effects of the localized plasmon resonance, the electricmultipoles, and the surface plasmon resonance. Specifically, in caseswhere only the localized plasmon resonance occurring with only the finegold particles 213, 213, . . . is utilized, the absorption andscattering spectral characteristics of the measuring light 223 becomeidentical with the absorption and scattering spectral characteristicsindicated by the broken line in FIG. 20. However, with this embodimentof the sensor in accordance with the present invention, the absorptionand scattering spectral characteristics of the measuring light 223become identical with the absorption and scattering spectralcharacteristics indicated by the solid line in FIG. 20. The absorptionand scattering spectral characteristics indicated by the solid line inFIG. 20 are such that the intensity of the reflected light changessharply with respect to a slight change in wavelength, i.e. a slightchange in refractive index of the sample liquid 221. Therefore, with thesensor described above, the refractive index of the sample liquid 221,the physical properties of the sample liquid 221 corresponding to therefractive index, and the like, are capable of being measured markedlyaccurately.

[0208] The characteristics illustrated in FIG. 20 are capable of beingdetermined previously in accordance with experience or experiments.

[0209] In the embodiment of the sensor described above, the measuringlight 223, which is the white light and has been reflected from the finestructure body 210, is detected spectrophotometrically, and theresonance peak wavelength λ_(LP) is thereby detected. Alternatively,monochromatic light may be employed as the measuring light, and theshift of the resonance peak wavelength λ_(LP) or the change in lightintensity accompanying the change in scattering and absorption of themeasuring light 223 may be detected. In such cases, the refractive indexof the sample liquid 221, the physical properties of the sample liquid221 corresponding to the refractive index, and the like, are capable ofbeing measured.

[0210] A fine structure body 230, which is a different embodiment of thefine structure body in accordance with the present invention, will bedescribed hereinbelow with reference to FIG. 21. The fine structure body230 is constituted basically in the same manner as that for the finestructure body 210 shown in FIG. 16, except that an antibody 231 isfixed previously onto the fine gold particles 213, 213, . . . and thethin gold film 214.

[0211] The fine structure body 230 is capable of being used in order toconstitute a biosensor illustrated in FIG. 22. The biosensor illustratedin FIG. 22 is constituted basically in the same manner as that for thebiosensor illustrated in FIG. 19, except that the fine structure body230 is used in lieu of the fine structure body 210. In this embodimentof the biosensor, a sample liquid 232 to be analyzed is introduced intothe vessel 220 such that the sample liquid 232 comes into contact withthe anodic oxidation alumina 212 of the fine structure body 230. In thiscase, the sample liquid 232 contains a specific antigen 233, which iscapable of undergoing specific binding with the antibody 231. In suchcases, as illustrated in FIG. 23, the antigen 233 is bound to theantibody 231 of the fine structure body 230.

[0212] In cases where the antigen 233 is bound to the antibody 231, therefractive index at the peripheral areas of the fine gold particles 213,213, . . . and the thin gold film 214 of the fine structure body 230changes. As a result, the absorption and scattering spectralcharacteristics of the measuring light 223 detected by thespectrophotometer 225 change. By way of example, as described above withreference to FIG. 4, the change in absorption and scattering spectralcharacteristics of the measuring light 223 detected by thespectrophotometer 225 appears as the shift of the resonance peakwavelength. Therefore, the change in resonance peak wavelength may bedetected by the spectrophotometer 225. In this manner, from the changein resonance peak wavelength, it is possible to find whether the bindingof the antibody 231 with the antigen 233 has or has not occurred, i.e.whether the antigen 233 is or is not present in the sample liquid 232.

[0213] With this embodiment of the biosensor, the near field light,which occurs when the measuring light 223 is irradiated to an area ofthe fine gold particles 213, 213, . . . , interacts with the thin goldfilm 214, and an absorption spectrum due to electric multipoles occurswith the measuring light 223. Further, the surface plasmon resonance isexcited by the interaction between the measuring light 223, which istotally reflected within the transparent anodic oxidation alumina 212,and the thin gold film 214. Therefore, the measuring light absorptionand scattering spectral characteristics alter sufficiently sharply dueto the synergistic effects of the localized plasmon resonance, theelectric multipoles, and the surface plasmon resonance. Accordingly, aslight binding of the antigen 233 with the antibody 231 is capable ofbeing detected accurately.

[0214] More specifically, examples of the combinations of the antibody231 and the antigen 233 include a combination of biotin andstreptoavidin, and the like. In such cases, in order for biotin to befixed more firmly to the fine structure body 230, the surface of theanodic oxidation alumina 212 should preferably be modified with aself-assembled monolayer. The self-assembled monolayer of this type isdescribed in detail in, for example, “Modeling Organic Surfaces withSelf-Assembled Monolayers” by Colin D. Brain and George M. Whitesides,Angewandte Chemie International Edition in English, Vol. 28, No. 4, pp.506-512, 1989.

[0215] A further different embodiment of the fine structure body inaccordance with the present invention and a further different embodimentof the third sensor in accordance with the present invention will bedescribed hereinbelow with reference to FIG. 24. In this embodiment, afine structure body 240 comprises an anodic oxidation alumina 212′, towhich the fine gold particles 213, 213, . . . and the thin gold film 214have been fixed. The anodic oxidation alumina 212′ takes on the formhaving been separated from the aluminum base plate 211 of the finestructure body 230 shown in FIG. 21. In this manner, the fine structurebody 240 is constituted of the anodic oxidation alumina 212′ acting asthe unit body. Alternatively, the anodic oxidation alumina 212′ may besecured to a different transparent member having a high rigidity, and afine structure body comprising the anodic oxidation alumina 212′ and thetransparent member may thus be constituted.

[0216] The sensor, in which the fine structure body 240 is used,comprises the fine structure body 240, a vessel 220′, the white lightsource 224, and the spectrophotometer 225. In this embodiment, thevessel 220′ is provided with transparent windows 222′, 222′, which areformed at the side surfaces that stand facing each other. Also, thewhite light source 224 is located in an orientation such that themeasuring light 223, which is the white light, enters through one of thetransparent windows 222′, 222′ into the vessel 220′. Further, thespectrophotometer 225 is located in an orientation such that thespectrophotometer 225 receives the measuring light 223, which has passedthrough the vessel 220′ and is radiated out from the other transparentwindow 222′. Furthermore, the fine structure body 240 is located at theposition such that the fine structure body 240 enters into the opticalpath of the measuring light 223 within the vessel 220′.

[0217] In the embodiment of the sensor illustrated in FIG. 24, thesample liquid 232 to be analyzed is introduced into the vessel 220′.Also, the measuring light 223 traveling within the vessel 220′ passesthrough the area of the fine gold particles 213, 213, . . . and the thingold film 214 of the fine structure body 240, which area is in contactwith the sample liquid 232. The measuring light 223 having passedthrough the area of the fine gold particles 213, 213, . . . and the thingold film 214 of the fine structure body 240 is detected by thespectrophotometer 225. Therefore, with this embodiment of the sensor, asin the cases of the sensor illustrated in FIG. 22, the occurrence of thebinding of the antibody 231 (indicated by the Y-shapedmark in FIG. 24)and the antigen 233 is capable of being detected.

[0218] A still further different embodiment of the fine structure bodyin accordance with the present invention and a still further differentembodiment of the third sensor in accordance with the present inventionwill be described hereinbelow with reference to FIG. 25. In thisembodiment, a fine structure body 250 is constituted basically in thesame manner as that for the fine structure body 240 shown in FIG. 24,except that the antibody 231 has previously be fixed also to the finegold particles 213, 213, . . . , which are exposed from a back surfaceof the anodic oxidation alumina 212′ (i.e., the right end face of theanodic oxidation alumina 212′ in FIG. 25) to the exterior of the anodicoxidation alumina 212′.

[0219] Also, the sensor illustrated in FIG. 25 is constituted basicallyin the same manner as that for the sensor illustrated in FIG. 24, exceptthat the fine structure body 250 is used in lieu of the fine structurebody 240. With the sensor illustrated in FIG. 25, as in the cases of thesensor illustrated in FIG. 24, the binding of the antibody 231 with theantigen 233 is capable of being detected accurately.

[0220] An even further different embodiment of the fine structure bodyin accordance with the present invention will be described hereinbelowwith reference to FIG. 26. In this embodiment, a fine structure body 260comprises a support member 261. The fine structure body 260 alsocomprises a plurality of anodic oxidation alumina bodies 212′, 212′, . .. , which are supported together with one another by the support member261. The anodic oxidation alumina bodies 212′, 212′, . . . are arrayedin a row at predetermined intervals. By way of example, each of theanodic oxidation alumina bodies 212′, 212′, . . . may be constituted inthe same manner as that for the anodic oxidation alumina 212′constituting the fine structure body 240 shown in FIG. 24. Though notshown in FIG. 26, as in the cases of the fine structure body 240, eachof the anodic oxidation alumina bodies 212′, 212′, . . . is providedwith the fine gold particles 213, 213, . . . and the thin gold film 214.Also, the antibody 231 has been fixed to the fine gold particles 213,213, . . . and the thin gold film 214.

[0221] In this embodiment of the fine structure body 260, by way ofexample, eight anodic oxidation alumina bodies 212′, 212′, . . . aresupported together with each other by the support member 261. The arraypitch of the anodic oxidation alumina bodies 212′, 212′, . . . is set tobe identical with the array pitch of wells 263, 263, . . . of amicro-titer plate 262. By way of example, the micro-titer plate 262 mayhave 8×12 (=96) holes. Therefore, each of the eight anodic oxidationalumina bodies 212′, 212′, . . . of the fine structure body 260 iscapable of being dipped in one of the eight wells 263, 263, . . . of themicro-titer plate 262, which are arrayed in one direction. In thismanner, different sample liquids 232, 232, . . . , which have beenaccommodated respectively in the wells 263, 263, . . . , are capable ofbeing simultaneously supplied to the anodic oxidation alumina bodies212′, 212′, . . . of the fine structure body 260.

[0222] After each of the different sample liquids 232, 232, . . . hasthus been supplied to one of the anodic oxidation alumina bodies 2121,212′, . . . of the fine structure body 260, the fine structure body 260is capable of being used in order to detect the binding of the antibody231 with the antigen 233 by use of, for example, the white light source224 and the spectrophotometer 225 as illustrated in FIG. 24 or FIG. 25.In such cases, the vessel 220′ for containing the sample liquid asillustrated in FIG. 24 or FIG. 25 becomes unnecessary.

[0223] Also, in cases where eight sets, each of which comprises thecombination of the white light source 224 and the spectrophotometer 225,are utilized simultaneously, the operations for irradiating themeasuring light and the operations for detecting the in tensity of thetransmitted light are capable of being performed simultaneously withrespect to the eight anodic oxidation alumina bodies 212′, 212′, . . . ,to which the different sample liquids 232, 232, . . . have beensupplied. Alternatively, only one set, which comprises the combinationof the white light source 224 and the spectrophotometer 225, maybeutilized, and the fine structure body 260 may be moved with respect tothe one set of the combination of the white light source 224 and thespectrophotometer 225. In this manner, the eight anodic oxidationalumina bodies 2121, 2121, . . . may be successively sent to the one setof the combination of the white light source 224 and thespectrophotometer 225 at short time intervals. In such cases, theoperations for irradiating the measuring light and the operations fordetecting the intensity of the transmitted light are capable of beingperformed efficiently with respect to the eight anodic oxidation aluminabodies 212′, 212′, . . .

[0224] As described above, with this embodiment of the fine structurebody 260, the operations for supplying the sample liquids, theoperations for irradiating the measuring light, and the operations fordetecting the intensity of the transmitted light are capable of beingperformed efficiently. Therefore, the analyses and the measurements withrespect a plurality of samples are capable of being performed quickly.

What is claimed is:
 1. A sensor chip, comprising: i) a layer-shaped basebody, which has a plurality of fine holes formed in one surface, and ii)fine metal particles, each of which is loaded in one of the fine holesof the base body, wherein at least a part of each of the fine metalparticles is exposed to a side of the layer-shaped base body, which sideis more outward than the one surface of the layer-shaped base body.
 2. Asensor chip as defined in claim 1 wherein the layer-shaped base body isconstituted of anodic oxidation alumina.
 3. A sensor chip as defined inclaim 1 wherein the fine holes of the layer-shaped base body are formedwith etching processing, in which anodic oxidation alumina having aplurality of fine holes is utilized as a mask.
 4. A sensor chip asdefined in claim 1 wherein at least a one-half part of each of the finemetal particles is exposed to the side of the layer-shaped base body,which side is more outward than the one surface of the layer-shaped basebody.
 5. A sensor chip as defined in claim 1 wherein a diameter of eachof the fine metal particles is at most 200 nm.
 6. A sensor using asensor chip as defined in claim 1, the sensor comprising: i) means forirradiating measuring light to an area of the fine metal particles ofthe sensor chip, and ii) photo detecting means for detecting intensityof the measuring light, which has passed through the area of the finemetal particles, or has been reflected from the area of the fine metalparticles.
 7. A sensor as defined in claim 6 wherein the means forirradiating the measuring light is means for producing white light asthe measuring light, and the photo detecting meansspectrophotometrically detects the intensity of the measuring light,which has passed through the area of the fine metal particles, or hasbeen reflected from the area of the fine metal particles.
 8. A sensorchip for use in a sensor wherein a state of localized plasmon resonanceat a surface of each of fine metal particles is detected by theutilization of light and wherein characteristics of a sample in thevicinity of each of the fine metal particles are thereby analyzed, thesensor chip comprising: i) a support member having a plurality ofindependent fine holes, which extend in a direction approximately normalto a surface of the support member, and ii) independent fine metalparticles, each of which is supported within one of the fine holes ofthe support member, wherein the support member is constituted of atransparent dielectric material having uniform density.
 9. A sensor chipas defined in claim 8 wherein the support member is constituted of apolystyrene.
 10. A process for producing a sensor chip, comprising thesteps of: i) forming an anodic oxidation alumina film on a surface of abase plate, which is constituted of a transparent dielectric material,the anodic oxidation alumina film having a plurality of first fineholes, which extend in a direction approximately normal to the surfaceof the base plate, ii) subjecting the base plate to etching processing,in which the anodic oxidation alumina film having been formed on thesurface of the base plate is utilized as a mask, a plurality of secondfine holes, each of which corresponds to one of the first fine holes,being thereby formed in the surface of the base plate, and iii)performing processing wherein, after the anodic oxidation alumina filmhas been removed from the surface of the base plate, a metal depositingoperation is performed on the base plate having the surface, in whichthe second fine holes have been formed, the metal depositing operationbeing performed from the side of the surface of the base plate, and ametal deposit layer having been formed on the surface of the base plateis then removed, whereby each of independent fine metal particles issupported within one of the second fine holes of the base plate.
 11. Asensor, comprising: i) a sensor chip as defined in claim 8, ii) a lightsource for producing light, such that the light impinges upon an area ofthe fine metal particles of the sensor chip, and iii) photo detectingmeans for detecting intensity of the light, which has passed through thearea of the fine metal particles of the sensor chip, or has beenreflected from the area of the fine metal particles of the sensor chip,wherein characteristics of a sample in the vicinity of each of the finemetal particles, each of which is supported within one of the fine holesof the support member, are analyzed in accordance with results ofmeasurement obtained from the photo detecting means.
 12. A sensor asdefined in claim 11 wherein the photo detecting means is aspectrophotometer.
 13. A fine structure body, comprising: i) alayer-shaped base body, which has a plurality of fine holes formed inone surface, ii) fine metal particles, each of which is loaded in one ofthe fine holes of the base body, and iii) a thin metal film formed onareas of the one surface of the layer-shaped base body, which areas arelocated around each of the fine holes of the layer-shaped base body,such that the thin metal film is located at a spacing, which isapproximately equal to at most a diameter of each of the fine metalparticles, from each of the fine metal particles.
 14. A fine structurebody as defined in claim 13 wherein the layer-shaped base body isconstituted of anodic oxidation alumina.
 15. A fine structure body asdefined in claim 13 wherein the fine holes of the layer-shaped base bodyare formed with etching processing, in which anodic oxidation aluminahaving a plurality of fine holes is utilized as a mask.
 16. A finestructure body as defined in claim 13 wherein the layer-shaped base bodyis transparent with respect to light irradiated to the layer-shaped basebody.
 17. A fine structure body as defined in claim 13 wherein thelayer-shaped base body is divided into a plurality of layer-shaped basesub-bodies, which are located at a spacing from one another and aresupported together with one another.
 18. A process for producing a finestructure body as defined in claim 13, comprising the steps of: i)obtaining the layer-shaped base body, which has the plurality of thefine holes formed in the one surface, and ii) performing vacuumevaporation processing from the side of the one surface of thelayer-shaped base body, whereby each of the fine metal particles isloaded in one of the fine holes of the base body, and the thin metalfilm is formed on the areas of the one surface of the layer-shaped basebody, which areas are located around each of the fine holes of thelayer-shaped base body.
 19. A process for producing a fine structurebody as defined in claim 13, comprising the steps of: i) obtaining thelayer-shaped base body, which has the plurality of the fine holes formedin the one surface, ii) performing plating processing on thelayer-shaped base body, each of the fine metal particles being therebyloaded in one of the fine holes of the base body, and iii) performingvacuum evaporation processing from the side of the one surface of thelayer-shaped base body, whereby the thin metal film is formed on theareas of the one surface of the layer-shaped base body, which areas arelocated around each of the fine holes of the layer-shaped base body. 20.A sensor using a fine structure body as defined in claim 13, the sensorcomprising: i) means for irradiating measuring light to an area of thefine metal particles and the thin metal film of the fine structure body,and ii) photo detecting means for detecting intensity of the measuringlight, which has passed through the area of the fine metal particles andthe thin metal film, or has been reflected from the area of the finemetal particles and the thin metal film.
 21. A sensor as defined inclaim 20 wherein the photo detecting means spectrophotometricallydetects the intensity of the measuring light, which has passed throughthe area of the fine metal particles and the thin metal film, or hasbeen reflected from the area of the fine metal particles and the thinmetal film.